1. Field of Invention
The present invention generally relates to a non-volatile memory device. More specifically, the present invention relates to a three-dimensional (3D) non-volatile memory device, a memory system including the same, and a method of manufacturing the same.
2. Description of Related Art
A memory device with a three-dimensional (3D) structure in which memory cells are arranged in a 3D manner for the purpose of high-integration of memory devices has been suggested. Memory devices with a 3D structure may effectively utilize an area of a substrate, and improve the degree of integration compared to a case in which memory cells are arranged in a two-dimensional (2D) manner. In particular, attempts to apply, to the 3D structure, a regular memory cell arrangement of a NAND flash memory device which is profitable to high integration among non-volatile memory devices, have been actively made.
The 3D non-volatile memory device includes a first region in which a plurality of memory strings are arranged, and a second region in which driving transistors for controlling the plurality of memory strings are formed.
The memory string includes a plurality of memory cells that are stacked along a vertical channel film protruding over a substrate. The memory string may further include a pipe connection transistor that is formed below the plurality of memory cells, and connects the plurality of memory cells stacked along a pair of vertical channel films. The pipe connection transistor includes a pipe channel film that is connected to the pair or vertical channel films, and a pipe gate that encloses the pipe channel film. Driving gates of the driving transistors may be formed on the same layer as that of the pipe gate. The pipe gate may be formed in the first region, and the driving gates may be formed in the second region.
As described above, when the pipe gate formed in the first region and the driving gates formed in the second region are formed on the same layer, the pipe gate and the driving gates may be simultaneously patterned. However, when the pipe gate and the driving gates are simultaneously patterned, reliability of a manufacturing process may be reduced.
FIGS. 1A to 1C are cross-sectional views showing a manufacturing method of a pipe gate and a driving gate of a conventional 3D non-volatile memory device.
Referring to FIG. 1A, as described above, an insulating film 103 is formed on a semiconductor substrate 101 including a first region (R1) and a second region (R2). Next, a conductive film 105 is formed on the insulating film 103. The conductive film 105 is used for forming a pipe gate and driving gates.
Next, pipe trenches (PT) are formed in the conductive film 105 by etching the conductive film 105. The pipe trenches (PT) define a region where a pipe channel film is to be formed. Subsequently, a sacrificial film 111 is formed on the entire structure including the pipe trenches (PT) so that the pipe trenches PT are completely filled with the sacrificial film 111. In this instance, the sacrificial film 111 may also be formed on the conductive film 105 in the second region (R2).
Referring to FIG. 1B, the sacrificial film 111 is patterned. Therefore, the sacrificial film 111 remains inside the pipe trenches (PT) of the first region (R1) as sacrificial patterns 111a. A residual substance 111b of the sacrificial film may remain on the conductive film 105 in the second region (R2) in which the pipe trenches (PT) are not formed.
Referring to FIG. 1C, an etching process for patterning the conductive film 105 is performed.
Therefore, a pipe gate (PG) in which the sacrificial patterns 111a are embedded is formed in the first region (R1), and the driving gates (DG) are formed in the second region (R2). The pipe gate (PG) may be a pattern which is separated in units of memory blocks, and the sacrificial patterns 111a are embedded inside the pipe gate (PG). A shape of the residual substance 111b of the sacrificial film which remains in the second region (R2) may be transferred to the driving gates (DG) while the pipe gate (PG) and the driving gates (DG) are patterned. In this case, a defect 105a in a part which connects the driving gates (DG) may occur.